Array substrate, liquid crystal display panel, and method for driving the liquid crystal display panel

ABSTRACT

Disclosed is an array substrate, a liquid crystal display panel, and a driving method. The array substrate includes a plurality of pixel units, which is arranged in a pixel matrix; and a plurality of data lines, which is arranged to run through the pixel units. With respect to each of the data lines inside of boundary data lines of the pixel matrix, two pixel units electrically connected thereto in sequence are located in adjacent rows and at adjacent columns in the pixel matrix. The array substrate improves an aperture ratio of the pixel unit, which contributes to improvement of the quality of images.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the priority of Chinese patentapplication CN 201510670494.9, entitled “Array substrate, liquid crystaldisplay panel, and method for driving the liquid crystal display panel”and filed on Oct. 16, 2015, the entirety of which is incorporated hereinby reference.

FIELD OF THE INVENTION

The present disclosure relates to the field of liquid crystal display,and in particular, to an array substrate, a liquid crystal displaypanel, and a method for driving the liquid crystal display panel.

BACKGROUND OF THE INVENTION

With the development of liquid crystal display technologies, higherrequirements are put forward for the quality of a picture displayed by aliquid crystal display device. Improvement in the brightness of theliquid crystal display device enables more natural and beautifulpictures displayed, and thus is an important content in enhancingpicture quality. The main measures for high brightness design includeincreasing the brightness of a backlight and improving the transmittanceof a display screen. Increasing an aperture ratio of a pixel unit caneffectively improve the transmittance of the display screen.

The aperture ratio of a pixel unit refers to a ratio of an effectivelight transmission area in the pixel unit of the liquid crystal displaydevice to an entire area of the pixel unit. Because signal wires fordriving switch elements are provided between pixel electrodes ofdifferent pixel units on an array substrate, and gaps formed between thesignal wires and the pixel electrodes will cause light leakage, it isnecessary to provide a black matrix on a CF substrate for lightshielding. However, the black matrix will seriously affect the apertureratio of the pixel unit.

At present, improvements that have been made to the black matrix includethe BM on array technology in which the black matrix is arranged on thearray substrate, and thinning of data line wiring. Among them, the blackmatrix can be arranged on the array substrate to reduce a size designedfor the black matrix while the requirements for cell alignment aresatisfied. However, such a technology is not widely spread due tomaterial limitations. And thinning of wiring will lead to insufficientdata write capacity and in-plane DC deterioration, and thus lead todeterioration of brightness uniformity, screen flickering, long-termresidual images and other adverse effects. Therefore, there is noeffective solution to the problem of decreased aperture ratio of thepixel unit caused by the black matrix.

To conclude the above, it is urgent to improve the black matrix, so asto improve the aperture ratio of the pixel unit.

SUMMARY OF THE INVENTION

One technical problem to be solved by the present disclosure is that itis necessary to improve a black matrix, so as to improve an apertureratio of a pixel unit.

In order to solve the above technical problem, an array substrate isfirst provided in an embodiment of the present disclosure, comprising: aplurality of pixel units, which is arranged in a pixel matrix havingrows and columns; and a plurality of data lines, which is arranged torun through the pixel units, each of the data lines capable ofsimultaneously driving a plurality of pixel units along a columndirection, wherein with respect to each of the data lines inside ofboundary data lines of the pixel matrix, two pixel units electricallyconnected thereto in sequence are located in adjacent rows and atadjacent columns in the pixel matrix.

Preferably, gaps formed between the plurality of pixel units areshielded with a common electrode layer provided on the array substrateto prevent light leakage.

Preferably, the data lines are arranged to run through center portionsof the pixel units.

Preferably, an n^(th) data line among the plurality of data lineslocated inside of the boundary data lines of the pixel matrix iselectrically connected in sequence to an n^(th) pixel unit in a(2m−1)^(th) row and an (n+1)^(th) pixel unit in a 2m^(th) row of thepixel matrix, m and n both being positive integers.

Preferably, an n^(th) data line among the plurality of data lineslocated inside of the boundary data lines of the pixel matrix iselectrically connected in sequence to an n^(th) pixel unit in a(2m−1)^(th) row and an (n−1)^(th) pixel unit in a 2m^(th) row of thepixel matrix, m being a positive integer, and n being a positive integergreater than 1.

Preferably, an n^(th) data line among the plurality of data lineslocated inside of the boundary data lines of the pixel matrix iselectrically connected in sequence to an n^(th) pixel unit in a(2m−1)^(th) row, an (n−1)^(th) pixel unit in a 2m^(th) row, an n^(th)pixel unit in a (2m+1)^(th) row, and an (n+1)^(th) pixel unit in a(2m+2)^(th) row of the pixel matrix, m being a positive integer, and nbeing a positive integer greater than 1.

The present disclosure further provides a liquid crystal display panel,comprising an array substrate, which includes: a plurality of pixelunits, which is arranged in a pixel matrix having rows and columns; anda plurality of data lines, which is arranged to run through the pixelunits, each of the data lines capable of simultaneously driving aplurality of pixel units along a column direction, wherein with respectto each of the data lines inside of boundary data lines of the pixelmatrix, two pixel units electrically connected thereto in sequence arelocated in adjacent rows and at adjacent columns in the pixel matrix.

According to another aspect, a method for driving a liquid crystaldisplay panel is provided, comprising the steps of: driving, in displayof a same picture frame, any two adjacent columns of pixel units withdriving signals of different polarities respectively; and driving, indisplay of any two consecutive picture frames, a same column of pixelunits with driving signals of different polarities respectively.

Preferably, during display of a picture frame, odd-numbered columns ofthe plurality of data lines are driven with positive-polarity drivingsignals, and even-numbered columns of the plurality of data lines aredriven with negative-polarity driving signals; and during display of anext picture frame of the above picture frame, odd-numbered columns ofthe plurality of data lines are driven with negative-polarity drivingsignals, and even-numbered columns of the plurality of data lines aredriven with positive-polarity driving signals.

Preferably, the positive-polarity driving signals are voltage signalsapplied to the pixel electrode and higher than a voltage applied to acommon electrode voltage, and the negative-polarity driving signals arevoltage signals applied to the pixel electrode and lower than thevoltage applied to the common electrode voltage.

Compared with the prior art, one or more of the embodiments describedabove can have the following advantages or beneficial effects.

The data lines are arranged in an inner region of the pixel unit, suchthat it is unnecessary to provide a black matrix for light-shielding,thereby improving the aperture ratio of the pixel unit and the qualityof images.

Other advantages, objectives, and features of the present disclosurewill be set forth to a certain extent, in the description which followsand, to a certain extent, will be apparent to those skilled in the artbased on observational study of the following description, or may betaught from implementation of the present disclosure. The objectives andother advantages of the present disclosure may be realized and obtainedby the structure particularly pointed out in the following description,claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are provided for further understanding of the presentdisclosure or the prior art, and constitute one part of the description.They serve to explain the present disclosure in conjunction with theembodiments, rather than to limit the present disclosure in any manner.In the drawings:

FIG. 1 schematically shows the structure of a pixel unit on an arraysubstrate in the prior art;

FIG. 2 schematically shows the structure of an array substrate accordingto an embodiment of the present disclosure;

FIGS. 3 (a) and (b) schematically show connection between and among datalines and pixel units according to the embodiment of the presentdisclosure;

FIG. 4 schematically shows polarity distribution of voltages on pixelelectrodes;

FIG. 5 schematically shows a principle for generation of verticalcrosstalk; and

FIGS. 6 (a) and (6) schematically show grayscale voltages applied to apixel unit during display of a special picture, wherein FIG. 6 (a)schematically shows grayscale voltages applied to a pixel unit in theprior art, and FIG. 6 (b) schematically shows grayscale voltages appliedto a pixel unit according to the embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure will be explained in detail with reference to theembodiments and the accompanying drawings in the following, whereby itcan be fully understood how to solve the technical problem by thetechnical means according to the present disclosure and achieve thetechnical effects thereof, and thus the technical solution according tothe present disclosure can be implemented. It is important to note thatas long as there is no conflict, all the technical features mentioned inall the embodiments may be combined together in any manner, and thetechnical solutions obtained therefrom all fall within the scope of thepresent disclosure.

The following embodiments are explained with reference to theaccompanying drawings specifically illustrating implementableembodiments of the present disclosure. Direction terms used in thepresent disclosure, such as “upper,” “lower,” “left,” and “right,” referto respective directions relative to the drawings only. Hence, thedirection terms used herein are intended to explain for understanding,rather than to limit the present disclosure.

FIG. 1 schematically shows the structure of a pixel unit on an arraysubstrate in the prior art, in which reference numbers 11, 12, and 13respectively represent a data line, a scan line, and a pixel electrode,and an area enclosed by a dotted line represents a switch element.Therein, the data line 11 is located on a same layer as a source and adrain of the switch element 14. The source of the switch element 14 iselectrically connected to the pixel electrode 13, and can provide agrayscale voltage signal to the pixel electrode 13. A gate of the switchelement 14 is located on a same layer as the scan line 12 and connectedto the scan line 12, and the scan line 12 provides a control signal tothe switch element 14 to turn it on or off. As shown in the figure, thedata lines 11 in the prior art are arranged parallel to each other atboundaries of a pixel unit. In addition, when pixel units of theabove-described structure are arranged in the form of a pixel matrix onthe array substrate, one data line 11 can be used to drive an entirecolumn of pixel units in the pixel matrix (not shown in FIG. 1).

It can also be seen from FIG. 1, when the data line 11 is disposedbetween adjacent pixel electrodes 13, in order to ensure that a signalon the data line 11 and a signal on the pixel electrode 13 do notinfluence each other, it is necessary to maintain a certain gap d1between the data line 11 and the pixel electrode 13. Therefore, when ablack matrix is provided, in order to prevent light leakage from the gapbetween the data line 11 and the pixel electrode 13, it is necessary toenable the black matrix to have a side width at least equal to 2*d1+d2,wherein d2 is a wiring width of the data line 11, as shown in FIG. 1,such that the black matrix can completely cover the gaps formed betweenthe two adjacent pixel electrodes 13. On the other hand, the blackmatrix is generally arranged on a CF substrate. With the considerationthat the CF substrate and the array substrate need to satisfy certainalignment precision in a cell procedure therebetween, it is necessary toleave a width margin for the side width of the black matrix based on theabove 2*d1+D2, so as to ensure that the black matrix is still able toreliably shade light after the array substrate and the CF substrate arefit together. In particular, for a large-sized and high-resolutionpanel, a relative shift between an upper substrate and a lower substrateis large, so that a wide black matrix is required for light shielding,thereby seriously lowering an aperture ratio of the pixel unit. In viewof the above-described problems, in an embodiment of the presentdisclosure, an array substrate is provided with such a structure that ablack matrix will be unnecessary for light shielding.

FIG. 2 schematically shows the structure of an array substrate accordingto an embodiment of the present disclosure, in which an area 20 enclosedby a rectangle dashed box represents one pixel unit. In the embodimentas shown in FIG. 2, reference numbers 21, 23, and 22 respectivelyrepresent a data line, a pixel electrode, and a metal layer. A gate of aswitch element, a scan line electrically connected to the gate, and acommon electrode layer COM provided on an array substrate arespecifically patterned on the metal layer. None of the above-mentionedstructures is shown in FIG. 2. This, however, does not affect thesolution of the embodiment of the present disclosure, nor will the formof the above-described structures limit the solution of the embodimentof the present disclosure.

As shown in FIG. 2, the data line 21 is not located at a boundary of thepixel unit 20 any longer. Instead, it penetrates an interior of thepixel unit 20 along a column direction of the pixel matrix, and isarranged below the pixel electrode 23. At the same time, the commonelectrode layer COM is used to shield the gap between two adjacent pixelunits 20, such that it will be unnecessary to provide a black matrix onthe CF substrate. Therein, the data line 21 is preferably arranged insuch a manner that it penetrates a center portion of the pixel unit 20(as shown in FIG. 2). This enables the data line 21 to be equally spacedfrom shielding wires formed by the common electrode layer COM located atboundaries of both sides of the pixel unit 20, thereby ensuringhomogeneous liquid crystal display.

After the data line 21 is moved inside of the pixel unit 20, the gapbetween two adjacent pixel units 20 will be reduced, which isadvantageous in reducing a light-shielding structure in size. And sincethe common electrode layer COM also provided on the array substrate isused to shield light, there is no problem concerning alignmentprecision. As a result, it is possible to reserve a smaller margin inconsideration of a margin to be reserved for a width of thelight-shielding structure. That is, an effective light transmission areamaintained in the pixel unit 20 is increased, and the aperture ratio ofthe pixel unit can thus be increased.

As FIG. 2 further shows, when the data line 21 is provided below thepixel electrode 23, an area of the data line 21 directly facing thepixel electrode 23 increases, and a capacitive coupling effect of aparasitic capacitance between the data line 21 and the pixel electrode23 thus increases. As a result, in display of a special picture (such asa gray bottom white box), relatively serious vertical crosstalk will begenerated, thereby deteriorating the effect of liquid crystal display.In order to solve such a problem, in the embodiment of the presentdisclosure, with respect to each of the data lines, two pixel unitselectrically connected thereto in sequence are in alternate permutation,i.e., the two pixel units are located in adjacent rows and at adjacentcolumns in the pixel matrix. At the same time, different drive modes areused to eliminate vertical crosstalk.

Specifically, as shown in FIG. 2, an n^(th) data line is electricallyconnected in sequence to an n^(th) pixel unit in a (2m−1)^(th) row ofthe pixel matrix and to an (n−1)^(th) pixel unit in a 2m^(th) row,wherein m is a positive integer, and n is a positive integer greaterthan one. That is, when the pixel matrix has m rows, the n^(th) dataline is electrically connected in sequence to an n^(th) pixel unit in afirst row of the pixel matrix, a (n−1)^(th) pixel unit in a second row,an n^(th) pixel unit in a third row, a (n−1)^(th) pixel unit in a fourthrow, . . . , an n^(th) pixel unit in an m^(th) row (when m is an oddnumber) or an (n−1)^(th) pixel unit in an m^(th) row (when m is an evennumber).

Further, boundary data lines of the pixel matrix are arranged atoutermost sides of all of the data lines. In the present embodiment, allthe data lines are arranged in parallel and extend in a columndirection. Thus, the boundary data lines of the pixel matrix correspondto a leftmost data line and a rightmost data line in the pixel matrix. Aplurality of data lines located between the leftmost data line and therightmost data line are defined as the plurality of data lines locatedinside of the boundary data lines of the pixel matrix. In the presentdisclosure, the boundary data lines of the pixel matrix are electricallyconnected only to the pixel units which are not electrically connectedto any other data lines and located at boundary columns or at adjacentcolumns of the boundary columns of the pixel matrix. In the presentembodiment as shown in FIG. 2, the first data line is electricallyconnected in sequence to a first pixel unit in a first row of the pixelmatrix, a first pixel unit in a third row, . . . , a first pixel unit inthe m^(th) row (when m is an odd number).

In other embodiments of the present disclosure, the data lines can beconnected to the pixel units in other forms as shown in FIGS. 3 (a) and(b). In FIG. 3 (a), an n^(th) data line is electrically connected insequence to an n^(th) pixel unit in a (2m−1)^(th) row and an (n+1)^(th)pixel unit in a 2m^(th) row of the pixel matrix, wherein m and n areboth positive integers. In FIG. 3 (b), an n^(th) data line iselectrically connected in sequence to an n^(th) pixel unit in a(2m−1)^(th) row, an (n−1)^(th) pixel unit in a 2m^(th) row, an n^(th)pixel unit in a (2m+1)^(th) row and an (n+1)^(th) pixel unit of a(2m+2)^(th) row of the pixel matrix, wherein m is a positive integer andn is a positive integer greater than 1.

When the array substrate of the above-described form is used tomanufacture a liquid crystal display panel, it is possible to improvethe aperture ratio of the pixel unit without any black matrix providedon the CF substrate, thereby improving the brightness of the liquidcrystal display panel and ameliorating liquid crystal display effects. Amethod for driving the liquid crystal display panel as described abovewill be provided below. This method can eliminate vertical crosstalk andfurther improves the quality of images.

The method for driving the liquid crystal display panel comprises thesteps of: driving, in display of a same picture frame, any two adjacentcolumns of pixel units with driving signals of different polaritiesrespectively; and driving, in display of any two consecutive pictureframes, a same column of pixel units with driving signals of differentpolarities respectively. Specifically, when one picture frame isdisplayed, all odd-numbered rows of the plurality of data lines aredriven with positive-polarity (or negative-polarity) driving signals,and all even-numbered rows of the plurality of data lines are drivenwith negative-polarity (or positive-polarity) driving signals. When anext picture frame following the above picture frame is displayed, allodd-numbered rows of the plurality of data lines are driven withnegative-polarity (or positive-polarity) driving signals, and alleven-numbered rows of the plurality of data lines are driven withpositive-polarity (or negative-polarity) driving signals. Therein, thepositive-polarity driving signals are voltage signals applied to thepixel electrode and higher than a voltage applied to a common electrodevoltage, and the negative-polarity driving signals are voltage signalsapplied to the pixel electrode and lower than the voltage applied to thecommon electrode voltage.

FIG. 4 schematically shows polarity distribution of voltages applied tothe pixel electrodes during display of a picture frame when the liquidcrystal display panel is driven by the driving method described above,wherein the data lines are connected to the pixel electrodes in a manneras shown in FIG. 2 or FIG. 3 (a). As FIG. 4 further shows, theabove-described driving method enables the polarities of any two pixelelectrodes located in adjacent rows and adjacent columns to be oppositeto each other in each picture frame. And the coupling effect of theparasitic capacitance between the data lines and the pixel electrodescan be canceled out each other when the polarities of two adjacent pixelelectrodes in the column direction are opposite to each other, therebyreducing vertical crosstalk. The display effect that can be achieved bythe above-described driving method will be described in the followingwith reference to FIGS. 5 and 6.

FIG. 5 schematically shows a principle for generation of verticalcrosstalk, which refers to a phenomenon that in display of some specialpictures by the liquid crystal display device, a picture at a regionwill affect a picture at another region. As shown in FIG. 5, a whiteregion B (grayscale 255) is indicated in a middle of gray background(grayscale 128). Then, in straight line 1, the gray background can bedivided into three regions A, C, and D in display effects, wherein ahigh potential on the pixel electrodes of an intermediate white region Bpulls high, by the capacitive coupling effect of the parasiticcapacitance between the data lines and the pixel electrodes, voltages onparts of the pixel electrodes in the region A and the region D. Thisrenders brightness of the region A and the region D different from thatof the region C, and vertical crosstalk thus occurs.

When an existing driving mode as shown in FIG. 6 (a) is used to displaythe above picture, grayscale voltages of the plurality of pixel units inthe straight line 1 are different depending on gray levels displayedthereby. Therein, the voltages applied to the pixel electrodes can bedivided into three levels. A voltage of grayscale 128 applied to theregion A and the region D located at two ends is lower, and a voltage ofgrayscale 255 applied to the region B located at a middle section ishigher. Voltage Vcom applied to the common electrode is constant. Whenthe voltage on one pixel electrode (or some pixel electrodes) changes,since a plurality of parasitic capacitances between the data lines andthe plurality of pixel electrodes satisfy a charge conservationprinciple, other pixel units around the pixel unit including said onepixel electrode will share such a change. That is, other pixel unitsaround said one pixel unit cannot display a set grayscale.

When the above-described picture is displayed by the driving method inthe embodiment of the present disclosure, the polarities of any twopixel electrodes located in adjacent rows and adjacent columns areopposite to each other in each picture frame. Therefore, the grayscalevoltages of the plurality of pixel units in the straight line 1 appearalternately with positive and negative polarities. As shown in FIG. 6(b), the voltages on the pixel electrodes are alternately positive andnegative, and differences between the voltages on the pixel electrodesand the voltage of the common electrode have an equal absolute value.The voltage Vcom applied to the common electrode is constant. When thevoltage on one or some of the pixel electrodes changes, a voltage changetriggered on the data line will be opposite. Such changes in voltagescan thus cancel each other, thereby reducing influences of the pixelunit including the pixel electrode on surrounding pixel units. As aresult, it is possible to reduce a capacitive coupling effect betweenthe data line and the pixel electrode, thereby reducing verticalcrosstalk and improving the quality of images.

The above embodiments are described only for better understanding,rather than restricting, the present disclosure. Any person skilled inthe art can make amendments to the implementing forms or details withoutdeparting from the spirit and scope of the present disclosure. The scopeof the present disclosure should still be subject to the scope definedin the claims.

1. An array substrate, comprising: a plurality of pixel units, which isarranged in a pixel matrix having rows and columns; and a plurality ofdata lines, which is arranged to run through the pixel units, each ofthe data lines capable of simultaneously driving a plurality of pixelunits along a column direction, wherein with respect to each of the datalines inside of boundary data lines of the pixel matrix, two pixel unitselectrically connected thereto in sequence are located in adjacent rowsand at adjacent columns in the pixel matrix.
 2. The array substrateaccording to claim 1, wherein gaps formed between the plurality of pixelunits are shielded with a common electrode layer provided on the arraysubstrate to prevent light leakage.
 3. The array substrate according toclaim 1, wherein the data lines are arranged to run through centerportions of the pixel units.
 4. The array substrate according to claim1, wherein an n^(th) data line among the plurality of data lines locatedinside of the boundary data lines of the pixel matrix is electricallyconnected in sequence to an n^(th) pixel unit in a (2m−1)^(th) row andan (n+1)^(th) pixel unit in a 2m^(th) row of the pixel matrix, m and nboth being positive integers.
 5. The array substrate according to claim1, wherein an n^(th) data line among the plurality of data lines locatedinside of the boundary data lines of the pixel matrix is electricallyconnected in sequence to an n^(th) pixel unit in a (2m−1)^(th) row andan (n−1)^(th) pixel unit in a 2m^(th) row of the pixel matrix, m being apositive integer, and n being a positive integer greater than
 1. 6. Thearray substrate according to claim 1, wherein an n^(th) data line amongthe plurality of data lines located inside of the boundary data lines ofthe pixel matrix is electrically connected in sequence to an n^(th)pixel unit in a (2m−1)^(th) row, an (n−1)^(th) pixel unit in a 2m^(th)row, an n^(th) pixel unit in a (2m+1)^(th) row, and an (n+1)^(th) pixelunit in a (2m+2)^(th) row of the pixel matrix, m being a positiveinteger, and n being a positive integer greater than
 1. 7. The arraysubstrate according to claim 1, wherein the boundary data lines of thepixel matrix include a leftmost data line and a rightmost data line inthe pixel matrix.
 8. The array substrate according to claim 7, whereinthe boundary data lines of the pixel matrix are electrically connectedonly to pixel units which are not electrically connected to any otherdata lines and located either at boundary columns or at adjacent columnsof the boundary columns of the pixel matrix.
 9. A liquid crystal displaypanel, comprising an array substrate, which includes: a plurality ofpixel units, which is arranged in a pixel matrix having rows andcolumns; and a plurality of data lines, which is arranged to run throughthe pixel units, each of the data lines capable of simultaneouslydriving a plurality of pixel units along a column direction, whereinwith respect to each of the data lines inside of boundary data lines ofthe pixel matrix, two pixel units electrically connected thereto insequence are located in adjacent rows and at adjacent columns in thepixel matrix.
 10. A method for driving a liquid crystal display panel,wherein the liquid crystal display panel comprises an array substrate,which includes: a plurality of pixel units, which is arranged in a pixelmatrix having rows and columns; and a plurality of data lines, which isarranged to run through the pixel units, each of the data lines capableof simultaneously driving a plurality of pixel units along a columndirection, wherein with respect to each of the data lines inside ofboundary data lines of the pixel matrix, two pixel units electricallyconnected thereto in sequence are located in adjacent rows and atadjacent columns in the pixel matrix, and wherein the method comprisesthe steps of: driving, in display of a same picture frame, any twoadjacent columns of pixel units with driving signals of differentpolarities respectively; and driving, in display of any two consecutivepicture frames, a same column of pixel units with driving signals ofdifferent polarities respectively.
 11. The driving method according toclaim 10, comprising: driving, during display of a picture frame,odd-numbered columns of the plurality of data lines withpositive-polarity driving signals, and even-numbered columns of theplurality of data lines with negative-polarity driving signals; anddriving, during display of a next picture frame of the above pictureframe, odd-numbered columns of the plurality of data lines withnegative-polarity driving signals, and even-numbered columns of theplurality of data lines with positive-polarity driving signals.
 12. Thedriving method according to claim 11, wherein the positive-polaritydriving signals are voltage signals applied to the pixel electrode andhigher than a voltage applied to a common electrode voltage, and thenegative-polarity driving signals are voltage signals applied to thepixel electrode and lower than the voltage applied to the commonelectrode voltage.